1. Field of Invention
The present invention relates to a method for bonding two ceramic or glass-ceramic plates and, more particularly, to a method for bonding two ceramic or glass-ceramic plates by two glass or glass-ceramic bonding materials of different thermal properties.
2. Related Prior Art
Glass is used to bond many materials such as metal, alloy, ceramic and crystallized glass. Glass is most often used to bond glass to metal.
To bond glass to metal, the glass is heated so that its interface with the metal is adequately wet. Then, the glass and the metal are cooled to the room temperature, and bonded together.
There are various types of glass and metal. To bond glass and metal together firmly, their thermal properties must be considered. The thermal coefficient of the glass must be matched with that the metal. Otherwise, there would be stress in the glass and the metal, and the bond would be broken if the stress exceeds a limit of strength of the glass.
Sometimes, it is intended to bond two plates together by glass while leaving a gap between them. The materials of the plates and the type of the glass must be carefully selected for the above-mentioned reasons. A spacer is often used to make the gap. It is however troublesome to use such a spacer.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.